Perhaps you could try getting in touch with Rhino Handmade to find a way to get access to the master tapes of classic quad albums. While companies may not be willing to lend out priceless and sometimes irreplacable multitrack tapes, they may be willing to lend out the pre-mixed quadraphonic masters. See if a company and/or the artists would be willing to grant license for that. There is obviously a market for this stuff, it just needs to be identified in the masses. The Eagles are a very popular band that I think their classic albums would sell well and they seem to be quadraphonic or surround friendly.